Laminar mats and a method of production thereof

ABSTRACT

A laminar mat comprises a rigid planar tile of moulded plastics material having on respective faces a planar layer integrated therewith during moulding of the tile, the planar layers each being of similar material. Non-adhesive integration of the planar layers during moulding eliminates the need for adhesive. The mat may be moulded so as to include one or more projections, recesses and living hinges.

The invention relates to laminar mats and a method of productionthereof. The invention is especially applicable, but not limited to,mats for computer accessories such as a computer mouse. The mats mayalso be used as table mats or other types of mat for supporting objectson surfaces so as to protect the surfaces.

Mats of the laminar kind are known which are manufactured from atransparent or translucent hard layer of a plastics material, such asPVC of approximately 200 to 400 μm, and an underlying printed layer. Thehard layer is usually bonded to a base of foam or other suitablematerial which provides a non-slip engagement between the mat and asurface on which the mat is supported for use. The hard layer confers adegree of rigidity to the mat and protects against damage to the surfaceof the mat by, for example, scuffs or dents. The relatively thick hardlayer can, however, diffract light from the printed image and reduce thebrightness of the print underneath. This, of course, reduces the effectof advertising on the mat.

An alternative form of mat includes a thinner upper layer (12 to 70 μm)of scuff-resistant, transparent plastic such as polypropylene (PP)bonded to an underlayer of (e.g. 200 gsm) printed paper. The combinedlayer is then bonded to a foam backing. The thinner transparent layerreduces the diffractive effect, but reduces the rigidity of the mat,causing it to have a cheaper feel and be more susceptible to damage. Themat therefore has a relatively short useful life before it needs to bereplaced.

During manufacture of conventional mats, the laminated upper layer isfixed by adhesive to a lower backing layer of foam material, and the matis cut to shape. The cutting of the laminated upper layer leaves a sharprough edge on the upper perimeter of the mat. This edge can beuncomfortable for the hands and wrists of those using the mouse mat.

There is a need in the art therefore for a mat of sufficient rigidity towithstand wear and tear and protect any underlying decorative,advertising or other print, but allow underlying printed matter to beclearly visible. Furthermore, a mat of relatively slimline design toreduce costs and a mat provided with a smooth, more rounded edge portionis desirable. There is a further need for a mat which can bemanufactured cheaply and quickly and which allows efficient attachmentof foam or other non-slip backing material to the mat.

According to the first aspect of the invention there is provided alaminar mat comprising a rigid planar tile of moulded plastics materialhaving on respective faces a planar layer integrated therewith duringmoulding of the tile, the planar layers each being of similar material.

The term rigid is used to describe the moulded tile as structurally selfsupporting. That is to say that the mat, when gripped at an edge andheld horizontal, will maintain its shape and not sag under its ownweight. Advertising logos or other printed matter may be printed on oneor both of the planar layers.

Preferably, the planar layers are of a plastics material, such aspolypropylene (PP) or oriented polypropylene (OPP). Additionally, oralternatively, the layers may be of paper or card.

The planar layers may be of laminar construction. The layers may includea layer of polyester.

The planar layers are of similar material so as to prevent distortion ofthe tile during moulding thereof, by reinforcing the upper and lowersurfaces of the tile by an equivalent amount. The arrangement alsoallows the tile to be moulded of low cost plastics material which mayotherwise distort when removed from the mould.

The mat may be provided with a projection extending from a face thereof.Such a projection is preferably formed during moulding of the tile viaappropriate configuration of the mould. The projection may be providedon an upper surface thereof with one or more recesses. Such recesses maybe used to locate components to the mat. The projection may be hollow soas to provide a recess in the opposing face of the mat. In such anembodiment the projection may be provided with a through hole to therecess on the other side thereof. The mat may be provided with aplurality of such projection/recess combinations.

The mat may be moulded so as to have one or more living hinges therein.In such an embodiment the mat may comprise a plurality of panelsinterconnected by living hinges. A mat thus formed may be folded into athree dimensional structure, for example a cube. Preferably the panelsare provided with latch means so as to enable the mat to maintain thestructure. The latch means may comprise interengageable projections andrecesses of the panels formed during moulding of the mat.

Where the mat is a mat for a computer mouse, one or both of the layersmay be covered with a suitable coating which has one of, or a pluralityof:

-   -   High grip properties; anti-static properties; non-slip        properties; for example to prevent the mat moving relative to        the floor or work surface on which it is placed. Taking the        example of a non-slip coating, this may be provided on one or        both of the planar layers prior to moulding of the tile.

Alternatively the non-slip coating may be applied to the tile aftermoulding by any appropriate means, for example by screen printing. Thenon-slip coating may substantially cover the layer to which it isapplied or, alternatively, may be in discrete patches. The coating maybe PVC based.

The layers may be relatively thin, for example a 30 μm thick layer oforientated polypropylene (OPP), as rigidity is provided by the mouldedplastics tile and the tension effect of the layers applied thereto.

The planar layers protect the mat from wear and tear, such as scuffing,and protect applied printed matter thereunder. Advantageously, the matcan be manufactured to have a relatively slimline construction whilstmaintaining strength and rigidity. In one embodiment the planar layersare transparent and sufficiently thin to give minimum light diffraction.

The upper planar layer of the mat, that is to say the layer which isintended to be uppermost when the mat is supported upon a surface, maybe textured in the mould in which the tile is moulded, part of the mouldbeing suitably formed to provide the desired texturing. The pressure ofthe plastics material in the mould against the intended upper layer ofthe completed mat during moulding of the tile causes the layer to beformed with the textured features of the part of the mould.

The lower planar may be textured in the mould, for example by havingridges, protrusions, or dimples, so as to improve friction between themat and the underlying surface on which it is supported for use. As withthe textured upper planar layer just described, part of the mould may besuitably formed to provide the desired texturing.

Where the mat is, for example, a mat for a computer mouse, its edges arepreferably, rounded down from the upper surface to provide a comfortableperiphery to the mat for the user of the mouse.

In a further embodiment, the mat may include a thicker non-slip backingmaterial. For that purpose the lower planar layer may include, on itsouter surface, heat activated adhesive means whereby the backingmaterial is fixed to the underside of the mat. Use of such adhesivemeans allows the mat to be aligned correctly on the non-slip backingmaterial before the adhesive is activated by a heating step, during themat's manufacture, which bonds the backing material to the mat.

The lower layer may comprise a laminate, preferably of at least threelaminae, for example:

-   -   A first lamina fixed at one side to the planar tile;    -   A second lamina of aluminium foil bonded to the opposite side of        the first lamina; and    -   A lamina of heat sensitive adhesive fixed to the external face        of the aluminium foil.

Any suitable type of backing material may be applied to be fixed to thelower layer by the heat activated adhesive means.

The mat may include decorative effects such as, but not limited to,metalisation effects, holograms, and lenticular surfaces. In oneembodiment the decorative effects may be printed on the planar layer orlayers, as desired. Alternatively the decorative effects may be producedduring moulding of the mat via appropriate shaping or texturing of themould, and accurate alignment of the planar layers therewith.

According to the second aspect of the invention, a method ofmanufacturing a laminar mat comprises inserting at least two planarlayers of similar material into a mould at opposed surfaces thereof,filling the mould with a molten plastics material between the planarlayers and allowing the plastics material to set to produce a planartile with said planar layers bonded to opposite surfaces thereof.

The method preferably has a single moulding step and produces laminarmats of relatively slimline construction with each constituent layerbeing produced at its effective minimum available production thickness.This allows the mat to be produced economically and quickly as the matis in a finished state upon leaving the mould. By integrating the planarlayers with the tile during moulding the need for adhesive iseliminated.

The method preferably includes the use of multi-impression tooling tomould a plurality of mats in a single moulding operation.

The method may further comprise the steps of:

-   -   including on one layer of the mat, heat-activated adhesive means        on a lamina of heat conductive material so that, the moulded mat        includes a heat-activated adhesive means;    -   After removing the moulded tile from the mould, positioning        backing material on said one layer of the tile using alignment        means to align the tile and backing material; and passing the        mat and aligned backing material under an induction head which        causes the heat-conductive lamina to heat-activate the adhesive,        bonding the said one layer of the mat to the backing material.

The heat conductive lamina is preferably aluminium foil.

The alignment means preferably comprises a formed edge of the mat whichpositively locates the backing material correctly with respect to thesaid one layer of the tile before the adhesive is heat activated to bondthat layer to the backing material.

Pressure may be applied to the opposite layer of the tile during theheat activation of the adhesive. The moulded mat may be removed from themould by robotic means.

The mould may include parts to allow texturing to be applied to one orboth of the layers.

According to a further aspect of the present invention there is provideda mould for the production of a laminar mat, the mould comprising twomould parts defining therebetween a cavity which is filled duringmoulding, one of said mould parts being provided with an injection port,wherein said injection port has a peripheral wall extending partiallyacross said cavity towards the other of said mould parts. The wall ofthe injection port acts to both to locate a planar layer in the mouldand to guide material injected through the port. The wall may bediscontinuous, for example castellated.

There now follows by way of example only a detailed description ofembodiments of the invention with reference to the accompanying drawingsof which:

FIG. 1 a shows a cross-sectional view of a laminar mat according to oneembodiment of the invention;

FIG. 1 b shows a close-up cross-sectional view A of the laminar mat ofFIG. 11 a;

FIG. 2 a shows a cross-sectional view of a laminar mat according to afurther embodiment of the invention;

FIG. 2 b shows a close-up cross-sectional view B of the laminar mat ofFIG. 2 a;

FIG. 3 shows a cross-sectional view of a mould adapted to form a laminarmat according to an embodiment of the invention;

FIGS. 4 a and 4 b show partial cross-sectional views of alternativemould configurations;

FIG. 5 shows a cross-sectional view of an alternative mould adapted toform a laminar mat according to an embodiment of the present invention;

FIG. 6 shows a plan view of a mat formed using a mould having similarfeatures to that shown in FIG. 5; and

FIG. 7 shows a perspective view of a cut-out laminar mat according to anembodiment of the invention

In FIGS. 1 a and 1 b the mat 1 comprises a moulded planar tile 2 ofpolypropylene. The tile 1 is, typically, approximately 1 mm thick.Before moulding of the tile, upper and lower planar layers 3, 4 arepositioned in the mould against opposed surfaces thereof so that, whenthe mat is subsequently moulded in the mould, the layers 3, 4 arerespectively fixed integrally to opposite, upper and lower, surfaces ofthe tile. Dimples are moulded in the lower surface of the tile whichproduce corresponding dimples 5 in the lower layer 4 fixed to thesurface. The dimples 5 assist in improving friction between the mat andan underlying surface on which it may be supported for use.

The layers 3, 4 each comprise a laminated structure of 3 sub-layers: alamina of oriented polypropylene (OPP) 6, typically 30 μm thick, closestto the surface of the tile, and a printed lamina 7 on the underside of athird lamina 8 of the oriented polypropylene (OPP), typically 20 μmthick. As an alternative to the OPP, a lamina of paper, for example 100gsm, may be used, as it is easier to print on the paper than it is onthe OPP lamina.

The rigidity of the mat is conferred by the plastics material of thetile 2, reinforced against bending or other distortion of the plasticsmaterial after moulding by virtue of the layers 3, 4 on its upper andlower surfaces. The layers offer a scuff-resistant cover to the surfacesof the mat and are generally transparent so that underlying print isclearly visible through the layers. In the mat shown, the tile, and thusthe upper layer 3, has its edges rounded down from the upper surface tothe lower surface to improve comfort for the user of the mat.

The upper layer 3 of the same construction as the lower layer 4 whichdoubles the available printing space on the mat. The outermost lamina ofeach layer can be selected to be of a suitable material to improvecontact with the mouse ball or underlying surface. Alternatively, thelayer may be coated with a suitable coat 9 conferring improved contactwith the mouse ball or underlying surface. Such a coat may be PVC basedand applied in discrete patches as shown in FIG. 1 b. The provision ofsuch a coat 9, depending upon its constitution, may typically increasethe static friction coefficient (SFC) of the side to which it is appliedby a factor of about 4 times.

Taking the example of a mat with an underside having a rubberised coatscreen printed thereto and an uncoated OPP top surface, the followingcharacteristics were observed. Using a first test surface of mattpainted, flat MDF with few surface features and a test weight of 1 Kgapplied to the mat to approximate the weight of a hand resting on themat, an average SFC of 6.7 was observed with the coated underside incontact with the test surface compared to an average SFC of 2.08 withthe mat inverted and the uncoated top surface in contact with the testsurface. Using a second test surface of gloss painted, flat metal withno surface features, average SFC's of respectively 8.86 and 1.88 wereobserved.

Texturing (not shown) may be applied to the upper layer 3 by a suitablytextured part of the mould. The texturing may improve contact with themouse ball, incorporate advertising and/or improve the decorativeappearance of the mat.

The lower layer 4 is evenly covered with dimples 5 to improve frictionbetween the mat and the underlying surface, such as a table top, onewhich the mat is supported for use.

A further embodiment of the mat according to the invention is shown inFIG. 2. The mat has a foam backing 10 to improve the grip of the mat ona supporting underlying surface. The foam backing 10 is attached to thelower layer of the mat after moulding of the plastics tile. In thisembodiment the mat has an arcuately down-turned peripheral edge 13 sothat it is of a shallow inverted tray form. This rebated edge is morecomfortable for the user as it presents a contoured smooth surface.

The lower layer 34 of the mat comprises an OPP lamina 6, typically 30 μmthick, following by an aluminium foil lamina 11, typically 7 μm thick,with a heat-activated adhesive lamina 12 attached thereto. After the mayhas been removed, conveniently robotically, from the mould, a layer ofbacking foam 10, typically 3 mm thick, is placed on the heat sensitivelayer using the down-turned edge 13 of the mat to locate the foamaccurately with respect to the mat within the confines of the edge. Thealigned tile and backing foam 10 is passed under an induction head toheat the aluminium foil and activate the heat-activated adhesive whichbonds the backing foam 10 to the mat 1.

No adhesive spreads to the surrounding, overlapping edge of the matduring fixing of the foam backing to the mat, as the laminae and backingare held in a fixed position relative to each other duringheat-activation of the adhesive.

Referring now to FIG. 3 there is shown a simplified cross-sectional viewof a mould, generally designated 20, for use in manufacturing a laminarmat in accordance with the present invention. The mould 20 comprises twohalves 22, 24. The following description will refer to upper 22 andlower 24 halves of the mould, however it will be understood that thisidentification of the mould halves is used for the sake of clarity andnot to imply any restrictions as to orientation of the mould 20. Bothmould halves 22,24 have a peripheral lip 26,28 defining in each half22,24 opposing recessed portions 30,32. Both halves 22,24 are mounted soas to be movable together to close the mould 20 prior to a mouldingoperation and apart to open the mould 20 and subsequently release amoulded mat. The lower mould half 24 is provided with an injection port34 to allow the injection of a plastics material. The port 34 enablesplastics material to be injected in a direction substantiallyperpendicular to the plane of the finished mat.

The injection port 34 is surrounded by a raised wall 35 which extendsfrom the recessed portion 32 of the lower mould. The wall 35 standsproud of the lip 28 but is sized such that, when the mould 20 is closed,there is a clearance between the top of the wall 35 and the recessedportion 30 of the upper mould half 22. The wall 35 acts to both guidethe plastics material during injection between the planar layers and tolocate the lower planar layer in the lower mould half 24. Location ofthe lower planar layer is achieved by locating the wall 35 in anaperture of the planar layer.

The mould 20 of FIG. 3 is configured so as to provide a laminar mathaving a raised projection. The projection may be used to mount anaccessory to the laminar mat. The accessory may be, for example, afigurine or a cable guide for a mouse cable. To achieve this, the uppermould half 22 is provided with a frusto-conical recess 36 and the lowermould half with a frusto-conical projection 38 arranged to fit therecess 36. The projection 38 and recess 36 are dimensioned such that,when the mould 20 is closed, a clearance is provided therebetween andinto which plastics material injected via the injection port 34 mayflow.

In use, planar layers, for example a three ply arrangement of orientedpolypropylene (OPP) and paper, are inserted into the recessed portions30,32 of each mould half 22,24. The planar layers are sized to fitclosely to the respective lip 26,28 of each mould half 22,24 so as toensure that the planar layers do not move relative to the mould halves22,24 or each other either before or during moulding of a laminar mat.Alternatively, the planar layers may be retained in the mould 20 byother means such as, for example, in-mould fixings such as pins, anelectrostatic charge, or a vacuum.

In the embodiment shown it will be understood that the planar layersinclude apertures which align with the frusto-conical projection andrecess 36,38, and through which the projection 38 passes when the mould20 is closed.

Once the planar layers have been inserted into the mould 20 the twomould halves 22,24 are closed and molten plastics material, for examplepolypropylene, is injected via the injection port 34. It will beunderstood that the planar layer of the lower mould half 24 is providedwith an aperture which, in use, is aligned with the injection port 34.Thus the molten plastics material is injected into the centre of themould 20 between the planar layers. As the plastics material isintroduced it urges the planar layers against their respective mouldhalves 22,24 and reduces the possibility of the planar layers becomingdistorted or folded during the moulding operation. The plastics materialflows between the frusto-conical projection and recess 36,38 so as toprovide a frusto-conical projection of the laminar mat having a wallthickness equal to the clearance between the projection and recess36,38. Once injection of the plastics material has been completed themould halves 22,24 are separated and the laminar mat removed.

FIGS. 4 a and 4 b show alternative mould configurations which may beutilised to provide a raised projection in a finished mat. Featurescommon to the mould 20 of FIG. 3 are designated with like referencenumerals. In FIG. 4 a the upper mould half 22 is provided with a recess36 while the lower mould half 24 is planar. It will be understood that amould having this configuration will form a mat having a solidprojection. In such an embodiment the upper planar layer may be providedwith an aperture which is alignable with the recess 36 or,alternatively, the planar layer may be weakened in the region of therecess. Where the planar layer is weakened, for example by scoring orthe provision of one or more cuts therein, the planar layer rupturesduring injection of the plastics material thereby allowing the recess 36to be filled.

FIG. 4 b shows yet a further embodiment of the mould 20 wherein theupper mould half 22 is provided with a recess 36 and the lower mouldhalf 24 with a projection 38. The projection 38 is further provided witha raised pin 39 which is receivable in a corresponding blind hole 37 ofthe recess 36. The pin and hole 37,39 enable a through hole to bemoulded in the projection of the mat.

FIG. 5 shows an alternative mould arrangement generally designated 40.For the sake of clarity features common to the mould 20 of FIG. 3 aredesignated with like reference numerals. As before the mould 40comprises upper and lower mould halves 22,24 each having a peripherallip 26. The mould halves 22,24 are provided with aligned projections andrecesses 42,44 which enable a planar laminar mat to be moulded withcorresponding projections and recesses therein. Again it will beunderstood that the planar layers used in conjunction with the mould 40are provided with apertures which align with the projections andrecesses 42,44.

The mould halves 42,44 are further provided with opposed projections46,48 which are sized such that, when the mould 40 is closed, aclearance is provided therebetween. These opposed projections 46,48enable a living hinge to be moulded in a laminar mat.

FIG. 6 shows a plan view of a laminar mat 50 moulded using a mouldhaving features as described above with reference to FIG. 4. The mat 50is composed of six panels 52 interconnected by living hinges 54 so as todefine a cruciform shape. The perimeter of each panel 52 is providedwith a projection or recess which may be engaged with a complementaryrecess or projection of another panel 52. It will thus be understoodthat the panels 52 may be folded about the living hinges 54 and securedby the inter engagement of appropriate projections and recesses to forma cube.

The cruciform shape of the mat 50 of FIG. 6 may be achieved by a cuttingor stamping operation as illustrated in FIG. 7. Here a lozenge shapedmat 56 is shown cut from a blank 58 having a more regular rectangularshape. By utilising a cutting operation to produce a laminar mat 56having desired dimensions means that reduces the degree of accuracyrequired in aligning the planar layers in the mould halves prior toinjection of the plastics material.

1. A laminar mouse mat consisting essentially of a rigid planar tile ofmoulded plastics material having upon respective upper and lowersurfaces respective upper and lower planar layers non-adhesively bondedtherewith, wherein the upper and lower planar layers are eachconstructed from the identical material to prevent distortion of thetile during moulding thereof, the upper planar layer is textured by amould during moulding of the mat, and the lower planar layer is providedwith an external non-slip coating which, in use, resists the mat movingrelative to the work surface upon which it is placed.
 2. A laminar mousemat as claimed in claim 1 wherein the planar layers comprise a plasticsmaterial.
 3. A laminar mouse mat as claimed in claim 2 wherein saidplastics material of the planar layers is polypropylene.
 4. A laminarmouse mat as claimed in claim 3 wherein said plastics material of theplanar layers is oriented polypropylene.
 5. A laminar mouse mat asclaimed in claim 1 wherein the planar layers comprise paper.
 6. Alaminar mouse mat as claimed in claim 1 wherein the planar layerscomprise cardboard.
 7. A laminar mouse mat as claimed in claim 1 whereinboth of the planar layers are laminated.
 8. A laminar mouse mat asclaimed in claim 7 wherein the planar layers include laminae made frommaterial selected from the following: plastics material, paper andcardboard.
 9. A laminar mouse mat as claimed in claim 8 wherein theplastics material of the planar layers is selected from polypropylene,oriented polypropylene or polyester.
 10. A laminar mouse mat as claimedin claim 7 wherein the planar layers each comprise three laminae.
 11. Alaminar mouse mat as claimed in claim 10 wherein the planar layers eachcomprise three laminae of oriented polypropylene.
 12. A laminar mousemat as claimed in claim 10 wherein the planar layers each comprise alamina of paper provided between laminae of oriented polypropylene. 13.A laminar mouse mat as claimed in claim 1 wherein at least one of theplanar layers includes a coating with anti-static properties.
 14. Alaminar mouse mat as claimed in claim 1 wherein the external non-slipcoating is formed by screen printing.